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Abstract:

A number of biometric systems and methods are disclosed. A system
according to one embodiment includes an illumination subsystem, an
imaging subsystem, and an analyzer. The illumination subsystem is
disposed to illuminate a target space. The imaging subsystem is
configured to image the target space under distinct optical conditions.
The analyzer is provided in communication with the illumination
subsystem, the imaging subsystem, and the three-dimensional subsystem.
The analyzer also has instructions to operate the subsystems to collect
substantially simultaneously a plurality of images of the object disposed
at the predetermined spatial location under multispectral conditions.

Claims:

1-13. (canceled)

14. A contactless biometric system comprising: one or more illumination
sources configured to illuminate a target space; a plurality of imagers
configured to receive light from the target space under multispectral
conditions, wherein each imager is configured to receive light from a
different subspace of the target space; and an analyzer communicatively
coupled with the one or more illumination sources and the plurality of
imagers, the analyzer configured to control the operation of the one or
more illumination sources and the plurality of imagers in order to
produce a multispectral image of an object placed within the target space
from the light received at any or all the imagers.

15. The contactless biometric system according to claim 14, wherein the
analyzer is further configured to control the imagers such that the
imagers simultaneously receive light from the target space under
multispectral conditions.

16. The contactless biometric system according to claim 14, wherein the
plurality of imagers are arranged substantially coplanar.

17. The contactless biometric system according to claim 14, wherein the
plurality of imagers include at least one wafer-level camera.

18. The contactless biometric system according to claim 14, wherein the
analyzer further comprises a plurality of processors, wherein each of the
plurality of imagers are coupled with at least one processor.

19. The contactless biometric system according to claim 14, wherein the
target space is adapted to receive a human hand.

20. The contactless biometric system according to claim 14, wherein a
first subset of the plurality of imagers is focused on a first focal
plane and a second subset of the plurality of imagers is focused on a
second focal plane.

21. The contactless biometric system according to claim 14, wherein the
target space is not defined by a platen.

22-24. (canceled)

25. A method for collecting a biometric image comprising: illuminating a
target space with one or more illumination sources; receiving light
scattered from a portion of a purported skin site of an individual
located within a first subspace of said target space with a first imager;
receiving light scattered from a portion of the skin site located within
a second subspace of said target space with a second imager; deriving a
multispectral image of at least a portion of an object within said target
space from the light received at either or both of the first imager and
the second imager; and determining the identity of the individual from
the multispectral image.

26. The method according to claim 25, further comprising performing a
liveliness function with the multispectral image.

27. The method according to claim 25, further comprising performing a
spoof-detection function with the multispectral image.

28. The method according to claim 25, further comprising deriving
spatially distributed multispectral characteristics from the
multispectral image.

29-33. (canceled)

34. A contactless biometric system comprising: an illumination subsystem
disposed to illuminate a predetermined spatial location in free space; an
imaging subsystem disposed to collect light scattered by a purported skin
site located within the predetermined spatial location; sensing means for
sensing when the purported skin site is placed substantially within the
predetermined spatial location; and an analyzer in communication with the
illumination subsystem, the imaging subsystem, and the sensing subsystem,
wherein the analyzer comprises instructions to operate the illumination
subsystem, the imaging subsystem, and the sensing subsystem to derive a
multispectral image of an object placed within the target space and
imaged by the one or more imagers.

35. The contactless biometric system according to claim 34, wherein the
sensing means and the imaging subsystem comprise a single subsystem.

36. The contactless biometric system according to claim 34, wherein the
sensing means includes stereoscopic imagers.

37. The contactless biometric system according to claim 34, wherein the
sensing means includes stereoscopic illuminators.

38. The contactless biometric system according to claim 34, wherein the
imaging subsystem comprises at least a first imager and a second imager
configured to image light from the predetermined spatial location
substantially simultaneously.

39. The contactless biometric system according to claim 34, wherein the
sensing means includes at least one imager and a color filter array with
a plurality of color mosaics, wherein each pixel of the imager
corresponds to one of the plurality of color mosaics such that each pixel
detects light associated with the corresponding color, and wherein the
analyzer includes instructions to monitor the levels of blue light
received at the imager through the color filter array and compute a
mathematical function on the levels of blue light in proportion with
levels of other light.

40. The contactless biometric system according to claim 39, wherein the
color filter array is a Bayer filter array.

41. A contactless biometric system comprising: an illumination subsystem
disposed to illuminate a predetermined spatial location in free space; an
imager configured to receive light scattered from an objected located
within the predetermined spatial, the imager comprising a plurality of
pixels; a color filter array comprising a plurality of color mosaics,
wherein each pixel of the imager corresponds to one of the plurality of
color mosaics such that each pixel detects light associated only with the
corresponding color mosaic, and an analyzer in communication with the
illumination subsystem and the imager, wherein the analyzer comprises
instructions to operate the illumination subsystem and the imager, and
wherein the analyzer includes instructions to monitor the levels of blue
light received at the imager through the color filter array and compute a
mathematical function on the levels of blue light in proportion with
levels of other light received at the imager.

Description:

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent application Ser.
No. 12/136,435, filed on Jun. 10, 2008, entitled "Contactless
Multispectral Biometric Capture," which is a non-provisional, and claims
the benefit, of commonly assigned U.S. Provisional Application No.
60/943,207, filed Jun. 11, 2007, entitled "Contactless Multispectral
Biometric Capture," the entirety of which is herein incorporated by
reference for all purposes.

[0002] This application is a continuation-in-part of U.S. patent
application Ser. No. 12/100,597, filed Apr. 10, 2008, entitled "Biometric
Detection Using Spatial, Temporal, And/Or Spectral Techniques," which is
a nonprovisional, and claims the benefit, of U.S. Provisional Patent
Application No. 60/911,007, filed Apr. 10, 2007, entitled "Spatial And
Temporal Biometric Detection," the entire disclosure of each of which is
incorporated herein by reference for all purposes.

[0003] This application is a continuation-in-part of U.S. patent
application Ser. No. 11/779,998, filed Jul. 19, 2007, entitled
"Multibiometric Multispectral Imager," which is a nonprovisional, and
claims the benefit, of U.S. Provisional Patent Application No.
60/832,233, filed Jul. 19, 2006, entitled "Whole-Hand Multispectral
Imager," the entire disclosure of each of which is incorporated herein by
reference for all purposes.

BACKGROUND

[0004] This application relates to biometrics. More specifically, this
application relates to methods and systems for using a various biometric
sensor.

[0005] "Biometrics" refers generally to the statistical analysis of
characteristics of living bodies. One category of biometrics includes
"biometric identification," which commonly operates under one of two
modes to provide automatic identification of people or to verify
purported identities of people. Biometric sensing technologies measure
the physical features or behavioral characteristics of a person and
compare those features to similar prerecorded measurements to determine
whether there is a match. Physical features that are commonly used for
biometric identification include faces, irises, hand geometry, vein
structure, and fingerprint patterns, which is the most prevalent of all
biometric-identification features. Current methods for analyzing
collected fingerprints include optical, capacitive, radio-frequency,
thermal, ultrasonic, and several other less common techniques.

[0006] Most existing fingerprint sensors rely on relatively high-quality
contact between the finger and the sensor to obtain images. Obtaining
adequate contact is both finicky and time-consuming because of factors
related to individual characteristics of users of the sensors, the
quality of the skin, and environmental variability. For some individuals
and under some circumstances, achieving adequate contact is impossible.
Ease of consistent fingerprint capture limits the effectiveness and scope
of applications that utilize fingerprint biometrics for identity
management. Furthermore, in some cultures and during specific public
health events, there is a negative perception of contact-based
fingerprinting. This was the case, for instance, during the SARS outbreak
in 2003.

[0007] Contact measurement is a fundamental requirement for many forms of
fingerprint acquisition, such as optical total internal reflectance, RF,
capacitance, thermal, and ultrasound techniques. There have been a small
number of fingerprint sensors that have been developed and marketed as
"noncontact" fingerprint sensors. In many cases, these sensors use a
pedestal or some other device to locate and stabilize the finger. Thus,
although the fingerprint region is not in contact with the sensor, other
portions of the finger are contacting the sensor, which compromises the
advantages that a true noncontact fingerprint sensor would embody.

[0008] Most existing fingerprint sensors are also susceptible to being
defeated through the use of artificial or altered fingerprint samples.
Although each fingerprint technology may be susceptible to only specific
types of artificial (or "spoof") samples, the effort required to spoof
most systems is fairly modest one the "trick" for doing so is known.

BRIEF SUMMARY

[0009] A biometric system is disclosed according to some embodiments. The
biometric system includes one or more illumination sources, a first
imager, a second imager and an analyzer. The one or more illumination
sources may be configured to illuminate at least a portion of a target
space. The target space may be located within free space, in some
embodiments, and/or defined partially be a platen or other mechanical
device, in other embodiments. In other embodiments, the target space is
configured to receive a human hand. The first imager may be configured to
receive light from at least a portion of the target space under a first
optical condition. The second imager may be configured to receive light
from at least a portion of the target space under a second optical
condition. The first optical condition is distinct from the second
optical condition. The analyzer may be communicatively coupled with the
one or more illumination sources and the plurality of imagers. The
analyzer may also be configured to control the operation of the one or
more illumination sources, the first imager, and the second imager in
order to produce a multispectral image of an object placed within the
target space from the light received at first imager and the second
imager. The first imager and the second imager may be controlled by the
analyzer, in one embodiment, to imager the target space substantially
simultaneously.

[0010] In various embodiments, the first imager is configured to receive
light from a first subspace of the target space and the second imager is
configured to receive light from a second subspace of the target space.
In other embodiments, the first imager is focused at a first focal plane
and the second imager is focused at a second focal plane, wherein the
first focal plane and the second focal plane are distinct. In other
embodiments, the biometric system may include a first processor coupled
with the first imager and a second processor coupled with the second
imager. In other embodiments, the biometric system includes a user
interface configured to substantially indicate at least a portion of the
target space to a user. In other embodiments, the biometric system
includes a presence detector and/or proximity detector configured to
detect the presence of an object within the target space and/or the
proximity of an object relative to the target space.

[0011] A method for collecting a multispectral biometric image is
disclosed according to various embodiments. At least a portion of a
target space is illuminated. The illumination may include various
illumination techniques, illumination conditions, and/or illumination
sources. Light is received from at least a portion of the target space
under a first optical condition. Light is also separately received from
at least a portion of the target space under a second optical condition
substantially simultaneously as light is received from the target space
under the first optical condition. The first optical condition and the
second optical condition, in some embodiments, are distinct. A
multispectral image of an object within the target space may be derived
from the light received under either or both of the first optical
condition and the second optical condition.

[0012] In some embodiments, an indication of at least a portion of the
target space is provided. In other embodiments the presence of an object
within the target space is detected. In other embodiments, the first
optical condition and the second optical condition are selected from the
group consisting of polarized light, total internally reflected light,
light with a specific wavelength, light within a specific wavelength
band, light from a subspace within the target space, and/or light from a
focal plane within the target space. In other embodiments, a first imager
provides a first image of at least a portion of the target space under
the first optical condition and a second imager provides a second image
of at least a portion of the target space under the second optical
condition. In another embodiment, the first image has a resolution
greater than the resolution of the second image.

[0013] Another biometric system is disclosed according to various
embodiments. An illumination means for illuminating a target space is
included. A first imaging means for imaging at least a portion of the
target space under a first optical condition and providing a first image
may also be included. A second imaging means for imaging at least a
portion of the target space under a second optical condition distinct
from the first optical condition and providing a second image may also be
provided. A processing means for controlling the illumination means, the
first imaging means and the second imaging means is also provided. The
processing means may be configured to derive a multispectral image from
the first image and the second image.

[0014] Presence sensing means may also be included in some embodiments,
for sensing the presence of an object within at least a portion of the
target space. In other embodiment the first optical condition and the
second optical condition may be selected from the group consisting of
polarized light, total internally reflected light, light with a specific
wavelength, light within a specific wavelength band, light from a
subspace within the target space, and/or light from a focal plane within
the target space. In yet other embodiments an indication means for
indicating at least a portion of the target space to a user is included.

[0015] A whole-hand biometric sensor is also provided according to various
embodiments. The whole-hand biometric sensor includes a platen, one or
more illumination sources, a first imager, a second imager and an
analyzer. The platen may be configured to receive a human hand and/or
include a surface that defines a target surface. The one or more
illumination sources may be configured to illuminate at least a portion
of the target surface. The first imager may be configured to receive
light from at least a portion of the target surface under a first optical
condition. The second imager may be configured to receive light from at
least a portion of the target surface under a second optical condition.
The first optical condition may be distinct from the second optical
condition. The analyzer may be communicatively coupled with the one or
more illumination sources and the plurality of imagers. The analyzer may
also be configured to control the operation of the one or more
illumination sources, the first imager, and the second imager in order to
produce a multispectral image of an object placed on the target surface
from the light received at first imager and the second imager.

[0016] In various other embodiments, the analyzer may be configured to
control the first imager and the second imager to provide images
substantially simultaneously. In other embodiments, the first imager may
be configured to image a first spatial location on the target surface and
the second imager may be configured to image a distinct second spatial
location on the target surface. Either or both of the first imager and
the second imager may include one or more optical elements selected from
the list consisting of a color filter, a color filter array, a linear
polarizer, a circular polarizer, a diffuser, a collimator, a gratings,
and a lens. The first imager may be focused at a first focal plane and
the second imager may be focused at a second distinct focal plane. Other
embodiments include a first processor coupled with the first imager and a
second processor coupled with the second imager. A user interface
configured to substantially indicate at least a portion of the target
space to a user may also be included according to various other
embodiments. A presence and/or proximity detector configured to detect
the presence and/or proximity of an object within and/or relative to the
target space.

[0017] A method for collecting a multispectral biometric image of a human
hand is also disclosed according to various embodiments. At least a
portion of a target surface of a platen is illuminated with one or more
light sources of various types and/or configurations. Light may be
received from at least a portion of the target surface under a first
optical condition. Light may be separately received from at least a
portion of the target surface under a second optical condition
substantially simultaneously as the light is received the target surface
under a first optical condition. The first optical condition and the
second optical condition may be distinct. A multispectral image of an
object within the target surface may be derived from the light received
under either or both of the first optical condition and the second
optical condition.

[0018] In various embodiments the first optical condition and the second
optical condition may be selected from the group consisting polarized
light, total internally reflected light, light with specific wavelength,
light within a specific wavelength band, light from a first subspace
within the target space, and/or light from a first focal plane within the
target space. In some embodiments the first imager provides a first image
of at least a portion of the target space under the first optical
condition and/or the second imager provides a second image of at least a
portion of the target space under the second optical condition. In other
embodiments the first image has a resolution greater than the resolution
of the second image.

[0019] Another biometric system is disclosed according to various
embodiments that includes illumination means for illuminating a target
space, a first imaging means, a second imaging means and processing
means. The first imaging means adapted for imaging at least a portion of
the target space under a first optical condition and providing a first
image. The second imaging means adapted for imaging at least a portion of
the target space under a second optical condition distinct from the first
optical condition and providing a second image. The processing means
adapted for controlling the illumination means, the first imaging means
and the second imaging means. The processing means may be configured to
derive a multispectral image from the first image and the second image.
Presence sensing means for sensing the presence of an object within at
least a portion of the target space may also be included in various
embodiments. In other embodiments, the first optical condition and the
second optical may be selected from the group consisting polarized light,
total internally reflected light, light with specific wavelength, light
within a specific wavelength band, light from a first subspace within the
target space, and/or light from a first focal plane within the target
space.

[0020] A biometric system is disclosed according to one embodiment that
includes one or more illumination sources, a plurality of imagers and an
analyzer. The one or more illumination sources are configured to
illuminate a target space, wherein the target space is located in free
space or relative to a platen. The plurality of imagers are configured to
receive light from the target space under multispectral conditions. Each
imager is configured to receive light from the target space under
different multispectral conditions. The different multispectral
conditions may include differences in illumination wavelength or
wavelengths, differences in imaging wavelength or wavelengths,
differences in illumination angle, differences in imaging angle,
differences in imaging resolution, differences in spatial coverage,
and/or differences in focal plane. The analyzer may be communicatively
coupled with the one or more illumination sources and the plurality of
imagers. The analyzer may also be configured to control the operation of
the one or more illumination sources and/or the plurality of imagers in
order to produce one or more multispectral image of an object placed
within the target space from the light received at any or all the
imagers. The system may also include a plurality of processors, such that
each imager is coupled with a processor.

[0021] A biometric system is disclosed according to one embodiment that
includes one or more illumination sources, a first and a second imager,
and an analyzer. The one or more illumination sources may be configured
to illuminate a target space. The first imager receives light from a
first subspace of said target space under a multispectral condition. The
second imager receives light from a second subspace of said target space
under a different multispectral condition. The first imager and the
second imager receive light substantially simultaneously. The analyzer
may be communicatively coupled with the one or more illumination sources,
the first imager, and the second imager. The analyzer may be configured
to control the operation of the one or more illumination sources, the
first imager, and the second imager in order to derive a multispectral
image of an object placed within the target space from light received at
either or both of the first imager and the second imager.

[0022] A method for collecting a biometric image is provided according to
another embodiment. A target space is illuminated with one or more
illumination sources. Light is received from a first subspace of said
target space with a first imager. Light is received from a second
subspace of said target space with a second imager. A multispectral image
is derived with at least a portion of an object within said target space
from the light received at either or both of the first imager and the
second imager.

[0023] A biometric system is disclosed according to one embodiment. The
biometric system includes a platen, one or more illumination sources, a
first imager, a second imager and an analyzer. The platen may be adapted
for placement of a purported skin site by an individual. The one or more
illumination sources may be configured to illuminate the skin site. The
first imager may be configured to receive light from a first zone of said
skin site under a multispectral conditions. The second imager configured
to receive light from a second zone of said skin site under another
multispectral conditions. The analyzer may be communicatively coupled
with the one or more illumination sources, the first imager, and the
second imager. The analyzer may be configured to control the operation of
the one or more illumination sources, the first imager, and the second
imager in order to derive a multispectral image of the skin site from
light received at either or both of the first imager and the second
imager.

[0024] A biometric system is disclosed according to another embodiment,
that includes one or more illumination sources, a plurality of imagers
and an analyzer. The one or more illumination sources may be configured
to illuminate a target space. The plurality of imagers may be configured
to receive light from the target space under multispectral conditions. At
least one imager receives light with a multispectral condition distinct
from the multispectral condition received with at least one other imager.
The analyzer may be communicatively coupled with the one or more
illumination sources and the plurality of imagers. The analyzer may be
configured to control the operation of the one or more illumination
sources and the plurality of imagers in order to produce a multispectral
image of an object placed within the target space from the light received
at any or all the imagers.

[0025] A biometric system is disclosed according to one embodiment, that
includes one or more illumination sources, a first imager, a second
imager, and an analyzer. The one or more illumination sources may be
configured to illuminate a target space. The first imager may be
configured to receive light from said target space under a first optical
condition. The second imager may be configured to receive light from said
target space under a second optical condition. The analyzer may be
communicatively coupled with the one or more illumination sources, the
first imager, and the second imager. The analyzer may be configured to
control the operation of the one or more illumination sources, the first
imager, and the second imager in order to derive a multispectral image of
an object placed within the target space from light received at either or
both of the first imager and the second imager.

[0026] A method for collecting a biometric image is disclosed according to
another embodiment. A target space is illuminated. Light is received from
the target space under a first optical condition. Light is received from
the target space under a second optical condition. A multispectral image
of an object within said target space is derived from the light received
under the first optical condition and/or the second optical condition.
The first and/or second optical condition may include illumination
wavelength or wavelengths, imaging wavelength or wavelengths,
illumination angle, imaging angle, imaging resolution, spatial coverage,
and/or focal plane.

[0027] A contactless biometric system is provided according to one
embodiment. The contactless biometric system may include one or more
illumination sources, one or more imagers and an analyzer. The one or
more illumination sources may be configured to illuminate a target space
located in free space. The one or more imagers may be configured to
collect light from at least a portion of the target space under different
multispectral conditions. The analyzer may be configured to
communicatively coupled with the one or more illumination sources and the
one or more imagers. The analyzer may be configured to control the
operation of the one or more illumination sources and the one or more
imagers in order to derive a multispectral image of an object placed
within the target space and imaged by the one or more imagers.

[0028] A method for collecting a biometric image is provided according to
another embodiment. The presence of an object is detected within a target
space located in free space. The object is illuminated within the target
space with one or more illumination sources. Light is received from the
target space at one or more imagers with different optical conditions. A
multispectral image of the object within said target space is derived
from the light received at the one or more imagers.

[0029] A contactless biometric system is provided according to another
embodiment that includes an illumination subsystem, an imaging subsystem,
sensing means, and an analyzer. The illumination subsystem may be
disposed to illuminate a predetermined spatial location in free space.
The imaging subsystem may be disposed to collect light emanating from the
predetermined spatial location. The sensing means may be configured to
sense when a purported skin site is placed substantially within the
predetermined spatial location. The analyzer may be in communication with
the illumination subsystem, the imaging subsystem, and the sensing
subsystem. The analyzer may comprises instructions to operate the
illumination subsystem, the imaging subsystem, and the sensing subsystem
to derive a multispectral image of an object placed within the target
space and imaged by the one or more imagers.

[0030] A method for collecting a biometric image is provided according to
one embodiment. An indication of the proximate location of a target space
in free space is provided. An object within the target space is
illuminated with one or more illumination sources. Light from the target
space is received at one or more imagers under multispectral conditions
and/or different optical conditions. A multispectral image of the object
within said target space may be derived from the light received at the
one or more imagers.

[0031] A biometric system is disclosed according to another embodiment
that includes conveying means, illuminating means, imaging means, and
logic means. The conveying means for conveying an indication of the
proximate location of a target space in free space. The illuminating
means for illuminating at least a portion of the target space. The
imaging means for receiving light from the target space under
multispectral conditions. The logic means for deriving a multispectral
image of an object within said target space from the light received by
the imaging means.

[0032] A biometric system is disclosed according to one embodiment that
includes a platen, one or more illumination sources, a first imager, a
second imager and an analyzer. The platen may be configured to receive a
human hand. The one or more illumination sources may be configured to
illuminate a hand placed on the platen. The first imager may be
configured to receive light from a first portion of the hand under
multispectral conditions. The second imager may be configured to receive
light from a second portion of the hand under multispectral conditions.
The an analyzer may be communicatively coupled with the one or more
illumination sources, the first imager, and the second imager. The
analyzer may be configured to control the operation of the one or more
illumination sources, the first imager, and the second imager in order to
derive a multispectral image of the first portion of the hand from light
received at first imager and derive a multispectral image of the second
portion of the hand from light received at second imager. In another
embodiment, a single multispectral image may be derived at the analyzer
from the light received at both the first and second imagers.

[0033] A biometric system is disclosed according to one embodiment, that
includes one or more illumination sources, a plurality of images, and an
analyzer. The one or more illumination sources may be configured to
illuminate a hand placed substantially within target space in free space.
The plurality of imagers may be configured to receive light from portions
of a hand placed substantially within the target space under
multispectral conditions. The analyzer may be communicatively coupled
with the one or more illumination sources and the plurality of imagers.
The analyzer may be configured to control the operation of the one or
more illumination sources and the plurality of imagers in order to derive
a multispectral image of the portions of the hand from light received at
the plurality of imagers.

[0034] A method for collecting a biometric image of a hand is also
provided according to one embodiment. A target space located in free
space is provided for the placement of a human hand by an individual. A
hand within the target space may be illuminated using one or more
illumination sources. Light from the hand may be received under
multispectral conditions using one or more imagers. At least one
multispectral image of at least one portion of the hand within the target
space is derived from the received light.

[0035] Embodiments provide a contactless biometric system. The system
comprises an illumination subsystem, an imaging subsystem, a
three-dimensional sensing subsystem, and an analyzer. The illumination
subsystem is disposed to illuminate a predetermined spatial location in
free space. The imaging subsystem is disposed to collect light emanating
from the predetermined spatial location. The three-dimensional sensing
subsystem is configured to sense when an object is substantially in the
predetermined spatial location. The analyzer is provided in communication
with the illumination subsystem, the imaging subsystem, and the
three-dimensional subsystem. The analyzer comprises instructions to
operate the subsystems to collect substantially simultaneously a
plurality of images of the object disposed at the predetermined spatial
location under multispectral conditions.

[0036] In some embodiments, the illumination subsystem comprises a
light-emitting diode. In some cases, the light-emitting diode may
comprise a white-light emitting diode. In some embodiments, the
illumination subsystem comprises multiple light-emitting diodes. In some
cases a plurality of light emitting diodes may emit light that is
substantially monochromatic. Such a plurality of light-emitting diodes
may comprise light-emitting diodes with substantially different
wavelength characteristics. A polarizer may also be disposed to polarize
light emanating from the light-emitting diode.

[0037] The imaging subsystem may comprise a plurality of imagers oriented
and focused on the predetermined spatial location. Optical filters may be
disposed to filter the wavelengths of light collected by at least one of
the plurality of imagers. At least one of the plurality of imagers may
incorporate a color filter array. A polarizer may be disposed to polarize
light collected by at least one of the plurality of imagers.

[0038] The three-dimensional sensing subsystem may comprise a plurality of
coherent illuminators that are oriented to overlap at the predetermined
spatial location.

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] A further understanding of the nature and advantages may be
realized by reference to the remaining portions of the specification and
the drawings, wherein like reference labels are used throughout the
several drawings to refer to similar components.

[0040] FIG. 1 illustrates a structure that may be used for a contactless
biometric sensor in one embodiment.

[0041]FIG. 2 illustrates a modular biometric sensor according to one
embodiment.

[0042] FIGS. 3A, 3B, 3C and 3D illustrate various views of a modular
biometric sensor apparatus according to one embodiment.

[0043] FIGS. 4A, 4B, 4C and 4D illustrate various views of a spatially
modular biometric sensor apparatus according to one embodiment.

[0044] FIG. 5 shows a block diagram of a biometric sensor system according
to one embodiment.

[0045] FIGS. 6A, 6B, 6C and 6D illustrate various views of a
multispectrally modular biometric sensor apparatus according to one
embodiment.

[0046] FIGS. 7A, 7B, 7C and 7D illustrate various views of a contactless
biometric sensor apparatus according to one embodiment.

[0047] FIGS. 8A, 8B, 8C and 8D illustrate various views of a
multispectrally modular, contactless biometric sensor apparatus with
imagers that focus on different imaging planes according to one
embodiment.

[0048] FIGS. 9A, 9B, 9C and 9D illustrate various views of a spatially
modular, contactless biometric sensor apparatus with imagers that focus
on different imaging planes according to one embodiment.

[0049] FIG. 10A illustrates a multispectral datacube of a finger generated
in accordance with various embodiments.

[0050] FIG. 10B illustrates four overlapping images of a finger from four
spatially modular imagers according to one embodiment.

[0055] FIGS. 14A, 14B, 14C and 14D illustrate various views of a spatially
and multispectrally modular, contactless biometric sensor apparatus
according to one embodiment.

[0056] FIGS. 15A, 15B, 15C and 15D illustrate various views of a spatially
and/or multispectrally modular, contactless biometric sensor apparatus
with imagers that focus on different imaging planes according to one
embodiment.

[0057] FIG. 16 shows a contactless biometric system user interface with a
holographic image of a hand according to one embodiment.

[0058] FIG. 17 shows a contactless biometric system user interface with a
light array according to one embodiment.

[0059] FIG. 18 shows an image of a hand with five zones imaged with a
spatially modular imagines system according to one embodiment.

[0060] FIG. 19 illustrates a multispectral datacube of a hand generated in
accordance with various embodiments.

[0061] FIG. 20 illustrates six overlapping images of a hand from four
spatially modular imagers according to one embodiment.

[0063] FIG. 22 shows a flowchart of a biometric detection using various
embodiments described herein.

[0064] FIG. 23 shows an image of a finger with a tattoo-like feature
according to one embodiment.

[0065] FIG. 24 shows an image of a hand with a number of moles and a scar
according to another embodiment.

DETAILED DESCRIPTION

[0066] A detailed description is provided below of examples of
multispectral systems that may accordingly be used in embodiments, but
such a description is not intended to be limiting since other techniques
may be used in alternative embodiments.

[0067] Overview

[0068] Embodiments disclosed herein provide methods and systems that allow
for the collection and processing of biometric measurements. These
biometric measurements may provide strong assurance of a person's
identity, as well as of the authenticity of the biometric sample being
taken. Such embodiments, for example, may be incorporated within a number
of different types of devices, such as cellular telephones, personal
digital assistants, laptop computers, and other portable electronic
devices, as well as stand-alone devices for physical or logical access.
The common characteristic of the methods and systems is the application
of multiple distinct optical configurations used to collect a plurality
of image data during a single illumination session, often the images are
collected simultaneously. In some embodiments, the images are collected
of a finger or a hand with or without a platen. In some instances,
methods and systems are provided for the collection and processing of
data using a sensor with two or more distinct imagers. In other
instances, the methods and systems disclosed pertain to data collected
using a sensor with a single camera or multiple cameras. Other
embodiments methods and systems are provided for spatially and
multispectrally modular imaging and imaging systems.

[0069] The sensors may provide for an information-rich dataset that
results in increased security and usability relative to conventional
sensors. The increased security derives from combining information from
multiple images that represent distinct optical characteristics of the
material being measured. These characteristics provide sufficient
information to be able to distinguish between living human skin and
various artificial materials and methods that might be used to attempt to
spoof the sensor. As well, increased security is derived from the aspect
that provides a mechanism to perform measurements across a wide range of
environmental and physiological effects. The robust and reliable sampling
means that system security standards do not have to be relaxed to
compensate for poor image quality.

[0070] Enhanced sensor usability is achieved by reducing the constraints
on the individual for precise contact and/or positioning, as well as the
requirement that the individual's skin has particular qualities.
Moreover, embodiments also rely on contactless systems. As well, the
ability to extract subsurface biometric information from images collected
under certain optical conditions provides a mechanism for performing
biometric determinations even in those cases where the surface features
are missing or damaged. In this way, the multispectral measurements made
in embodiments are advantageously robust to non-ideal skin qualities,
such as dryness, excess wetness, lack of resilience, and/or worn features
such as are typically associated with the elderly, those who perform
significant manual labor, or those whose skin is exposed to chemicals,
such as hairdressers or nurses.

[0071] The set of all images collected under a plurality of distinct
optical conditions and/or during a single illumination session is
referred to herein as "multispectral data." The different optical
conditions may include differences in polarization conditions,
differences in illumination angle, differences in imaging angle,
differences in color filter array characteristics, differences in
resolution, differences in focal planes, differences in spatial coverage,
and/or differences in illumination wavelength or wavelengths. In some
optical conditions the resulting images are significantly affected by the
presence and distribution of TIR phenomena at the interface between the
sample and a platen. These images are referred to herein as "TIR images."
In some optical conditions, the resulting images are substantially
unaffected by the presence or absence of TIR effects at a platen. These
images are referred to herein as "direct images." Some embodiments
provide images that are taken without a platen, support (for example, the
support described in U.S. Pat. No. 6,404,904), contact point, mechanical
positioning device, mechanical alignment device, prop, etc. These images
are referred to herein as "contactless images." Contactless images are
created without physical contact between the skin site and the imaging
device, biometric sensor, and/or any accessory thereof.

[0072] Skin sites applicable to the multispectral measurements described
herein include all surfaces and all joints of the fingers and thumbs, the
fingernails and nail beds, the palms, the front of a hand or hands, the
back of a hand or hands, the wrists and forearms, the face, the eyes, the
ears, and all other external surfaces of the body. While the discussion
below sometimes makes specific reference to "fingers" or "hands" in
providing examples of specific embodiments, it should be understood that
these embodiments are merely exemplary and that other embodiments may use
skin sites at other body parts.

[0073] In some embodiments, a sensor provides a plurality of discrete
wavelengths of light that penetrate the surface of the skin, and scatter
within the skin and/or underlying tissue. As used herein, reference to
"discrete wavelengths" is intended to refer to sets of wavelengths or
wavelength bands that are treated as single binned units--for each binned
unit, information is extracted only from the binned unit as a whole, and
not from individual wavelength subsets of the binned unit. In some cases,
the binned units may be discontinuous so that when a plurality of
discrete wavelengths are provided, some wavelength between any pair of
the wavelengths or wavelength bands is not provided, but this is not
required. In some instances, the wavelengths are within the
ultraviolet--visible--near-infrared wavelength range.

[0074] A portion of the light scattered by the skin and/or underlying
tissue exits the skin and is used to form an image of the structure of
the tissue at or below the surface of the skin. In some embodiments, such
an image may include a fingerprint and/or hand image, where the term
"fingerprint" is used broadly herein to refer to any representation of
any skin site with dermatoglyphic features.

[0075] FIG. 1 shows an example of contactless modular biometric sensor 100
according embodiments. The biometric sensor 100 includes a plurality of
imagers 130 are arranged around a single light source 120 and position
sensors 108. A hand 116 placed with a predefined target space located
above the biometric sensor 100 may be imaged using the plurality of
imagers 104. The position of the hand relative to the biometric sensor
100 may be monitored using the position sensors 108. The position sensors
108 may include stereoscopic light sources, for example laser LEDs, that
illuminate the free space, including the target space, above the
biometric sensor 100. For example, in conjunction with one or more
imagers 104, stereoscopic light sources may provide an indication when
the hand is within the target space. The target space may include a
volume within free space where an object is substantially in focus at
least one imager when the object placed therein. Thus, a target space, in
some embodiments, may depend on the characteristics of the imager(s). In
one embodiment, an imager may be positioned to image different spatial
areas of the hand. In another embodiment, an imager may be positioned to
image the same portion of the hand but under different multispectral
conditions. In another embodiment, an imager may be positioned to image
different focal planes. In another embodiment, an imager may image at
substantially the same time. The resultant images may be combined using
any function to derive a multispectral image.

Spatially Modular Finger Sensor

[0076] Various embodiments provide for a spatially modular biometric
sensing system. As noted above, a multispectral image can be derived from
images with different spatial coverage. That is, spatially modular
imagers may be used to derive a multispectral image. FIG. 2 shows a
spatially modular biometric system according to one embodiment. The
system includes two imagers 230. The imagers 230A and 230B may be
separated or combined on a single circuit board, for example, as
conjoined wafer-level cameras. Each imager may also include various
optical elements 235. While three optical elements 235 are shown, any
number including zero may be used. At least one illumination source 220
may be used. In this embodiment, two LEDs 220 are used to illuminate the
finger 205 on the platen 210. The first imager 230A may receive light
from a first portion of the finger 205. The second imager 230B may
receive light from a second portion of the finger 205 placed on the
platen 210. The first portion and the second portion may overlap or be
completely distinct.

[0077] FIGS. 3A, 3B, 3C and 3D illustrate various views of another modular
biometric sensor apparatus according to one embodiment. The modular
sensor apparatus includes four imagers 330, optical elements 335, and
four light sources 320. While four light sources are shown, any number of
light sources may be used. For example, a single white light source may
be used. Each imager 330 receive light from four subsections of the
target area. These subsections may overlap or be distinct. As shown, a
finger 205 is placed on the target surface 212 of a platen 210. Each
imager may image four different parts of the finger. The imagers 330 may
image each subsection substantially simultaneously.

[0078] FIGS. 4A, 4B, 4C and 4D illustrate various views of a spatially
modular biometric sensor apparatus according to another embodiment. Four
imaging subsections 450 are shown in FIGS. 4B, 4C and 4D. Some overlap
between the subsections is shown in this embodiment. Subsections without
an overlap may also be used according to another embodiment. Such a
system may produce four images, like those shown in FIGS. 10A, 10B and
10C.

[0079] FIG. 5 shows a block diagram of a biometric sensor system 500
including a computational device and peripheral devices according to one
embodiment. The figure broadly illustrates how individual system elements
may be implemented in a separated or more integrated manner. Moreover,
the drawing also illustrates how each of the four imagers 510 may include
a dedicated processor 515 and/or dedicated memory 520. Each dedicated
memory 520 may include operational programs, data processing programs,
and/or image processing programs operable on the dedicated processors
515. For example, the dedicated memory 520 may include programs that
control the dedicated imager 510 and/or provide image processing. The
computational device 502 is shown comprised of hardware elements that are
electrically coupled via bus 530. The bus 530, depending on the
configuration, may also be coupled with the one or more LED(s) 505, a
proximity sensor (or presence sensor) 512 and four imaging subsystems 504
according to various embodiments. In another embodiment, imager memory
520 may be shared amongst imagers 515 and/or with the computational
device 502.

[0080] In such embodiments, an imaging subsystem may include an imager
510, a processor 515, and memory 520. In other embodiments, an imaging
subsystem 504 may also include light sources and/or optical elements.
Imaging subsystems 504 may be modular and additional imaging subsystems
may be easily added to the system Thus, biometric sensor subsystems may
include any number of imaging subsystems 504. The various imaging
subsystems, in one embodiment, may be spatially modular in that each
imaging subsystem is used to image a different spatial location. The
various imaging subsystems, in another embodiment, may be multispectrally
modular in that each imaging subsystem is used to image a different
multispectral condition. Accordingly, in such an embodiment, an imaging
subsystem 504 may also include various optical elements such as, for
example, color filter arrays, color filters, polarizers, etc., and/or the
imager 510 may be placed at various angles relative to the imaging
location. The various imaging subsystems, in another embodiment, may
provide focus modularity in that each imaging subsystem is used to image
a different focal point or focal plane.

[0081] The hardware elements may include a central processing unit (CPU)
550, an input/output device(s) 535, a storage device 555, a
computer-readable storage 540, a network interface card (NIC) 545, a
processing acceleration unit 548 such as a DSP or special-purpose
processor, and a memory 560. The computer-readable storage 540 may
include a computer-readable storage medium and a computer readable medium
reader, the combination comprehensively representing remote, local,
fixed, and/or removable storage devices plus storage media for
temporarily and/or more permanently containing computer-readable
information. The NIC 545 may comprise a wired, wireless, modem, and/or
other type of interfacing connection and permits data to be exchanged
with external devices.

[0082] The biometric sensor system 500 may also comprises software
elements, shown as being currently located within working memory 560,
including an operating system 565 and other programs and/or code 570,
such as a program or programs designed to implement methods described
herein. It will be apparent to those skilled in the art that substantial
variations may be used in accordance with specific requirements. For
example, customized hardware might also be used and/or particular
elements might be implemented in hardware, software (including portable
software, such as applets), or both. Further, connection to other
computing devices such as network input/output devices may be employed.

[0083] Multispectrally Modular Finger Sensor

[0084] FIGS. 6A, 6B, 6C and 6D illustrate various views of a
multispectrally modular biometric sensor apparatus according to one
embodiment. As shown in this embodiment, each of the four imagers 630, in
conjunction with optional optical elements 635, image most, if not all of
the target area 212 where the finger 205 is located on the platen 210.
The imagers 630 may image the target area 212 substantially
simultaneously. The imagers 630, in this embodiment, may record images
under various multispectral conditions, such as, for example, distinct
polarization, distinct imaging angle, distinct wavelength or wavelengths,
TIR conditions, distinct resolution, distinct focal planes, distinct
spatial coverage, color filter array filtering, etc. For example, a first
imager 630A may be associated with a linear polarizing optical element
635A. A second imager 630B may be a high resolution imager 635B that
images, for example, with a resolution greater than 200 dots per inch. A
third imager 630C may be associated with a Bayer filter as an optical
element 635C. A fourth imager may be associated with a blue color filter
optical element 635D. While the imagers 630 and the associated optical
elements 635 are shown in the figure relatively close together,
relatively coplanar and relatively parallel with the platen, one or more
imagers and the associated optical elements may be located at an angle
relative to the platen 210 and/or target area 212 in one embodiment.
Moreover, one or more imagers may be placed in a non-coplanar
configuration in another embodiment. Also, in yet another embodiment, one
or more imagers may be configured to image light that undergoes total
internal reflection at the interface of the finger 205 with the platen
target area 212. While four imagers are shown, any number of imagers 630
may be added to the system. Various imagers may provide distinct and/or
unique images of the target area under various multispectral optical
conditions.

[0085] The various imagers may image a finger 205 in the target area 212
substantially simultaneously under the same illumination condition. For
example, a while light source or sources may illuminate the finger and
each imager may record an image of the finger 205 under various optical
conditions. Simultaneous or substantially simultaneous imaging may
provide a consistent set of images of the finger 205 that removes,
mitigates, or minimizes the affect of any finger jitter, motion, ambient
variations, etc., from the various images. Thus, finger characteristics
may correspond well from image to image. In one embodiment, the
integration time of the imagers, during which an image is recorded,
overlap. In another embodiment, the imagers may image at the same time.
For example, each frame imaged at a first imager may be synched with a
frame at a second imager. In another embodiment, the imagers record an
image within less than one second of each other. In another embodiment,
the imagers record an image within less than 500 microseconds of each
other. In another embodiment, the imagers record an image within less
than 100 microseconds of each other.

[0086] In another embodiment, the imagers may provide continuous imaging
In some embodiments, each imager is synched to image at relatively the
same time. For example, the imagers may record images with a video frame
rate of 15, 30, 60, or 75 Hz. The imagers may be synched by a clocked
signal from a processor and/or clock. If the imagers are properly synched
together, a single frame from each imager may be saved into memory that
is synched with the frames from the other imagers. For example, the frame
may be chosen for storage based on focus, relative location of the skin
site, jitter, orientation, contrast, skin site motion, lighting, ambient
effects, imager effects, etc. In another embodiment, a set of frames is
recorded into memory. A single synched frame may be selected from each
imager and used to derive a multispectral image.

[0087] The embodiments described throughout this disclosure may produce a
set of images of the finger and/or hand under different optical
conditions or produce data from which such a set may be produced using
reconstruction techniques. For purposes of illustration, the following
discussion is made with reference to such a set of multispectral images,
although it is not necessary to produce them for subsequent biometric
processing in those embodiments that do not generate them directly. In
general, the images collected by the device described in this disclosure
may differ in polarization conditions, image angle and location, as well
as spectral properties. Furthermore, in the case of a color imager
comprised of a color filter array, the color images may be extracted as
subarrays of the raw pixel values or may be color-interpolated values, as
known to one familiar in the art. The images from the plurality of
imagers may need to be aligned, tiled, shifted and/or otherwise
preprocessed prior to further processing. An illustrative set of aligned
and processed multispectral images is shown in FIG. 10A, with the set
defining a multispectral datacube 1000.

[0088] One way to decompose the datacube 1000 is into images that
correspond to each of the multispectral conditions used to image the
sample in the measurement process. In the figure, five separate images
10005, 1010, 1015, 1020, and 1025 are shown, corresponding to five
discrete multispectral conditions. In an embodiment where visible light
is used, the images might correspond, for example, to images generated
using light at 450 nm, 500 nm, 550 nm, 600 nm, and 650 nm. For example,
the illumination source includes a broadband white light sources and/or
each imager may include a color filter. In other embodiments the images
may represent polarization conditions, imaging angle, resolution, spatial
modularity, focal plane modularity, and/or TIR conditions. In some
embodiments, each image may represent the optical effects of light of a
particular wavelength interacting with skin and. Due to the optical
properties of skin and skin components that vary by wavelength,
polarization, and/or angle of imaging, each of the multispectral images
10005, 1010, 1015, 1020, and 1025 will be, in general, different from the
others.

[0089] In some embodiments, each of the multispectral conditions
correspond to a different wavelength or wavelengths of light.
Accordingly, the datacube may thus be expressed as R(XS, YS,
XI, YI, λ) and describes the amount of diffusely
reflected light of wavelength λ, seen at each image point XI,
YI when illuminated at a source point XS, YS. Different
illumination configurations (flood, line, etc.) can be summarized by
summing the point response over appropriate source point locations. A
fingerprint or handprint image F(XI, YI) can loosely be
described as the multispectral data cube for a given wavelength,
λo, and summed over all source positions:

The multiple images collected from a single acquisition event may thus be
post-processed to produce a single composite fingerprint image that is
fully compatible with conventionally collected "standards-based" legacy
fingerprint databases. In addition the multispectral images may be used
to ensure that the sample has optical properties consistent with a living
human finger. The composite image and the liveliness assessment may be
reported by the analyzer 108.

[0090] Contactless Finger Sensor

[0091] A contactless biometric sensor does not include a platen that
defines a target space where illumination sources and/or imagers are
focused and/or where a sample may be placed for imaging. Instead, the
imagers and/or illumination sources may be focused at a target space that
is defined within free space without definition with a platen or any
other physical element or device. A user may place their hand and/or
finger(s) within the target space without touching, contacting, and/or
referencing a platen. In some embodiments the biometric system and/or
device may include a window between at least some of the optical
elements, for example, imagers and/or illumination sources, and the
target space. Such a window may be used to seal the optical elements for
protection from the elements and to keep the area clean. Such a window
should not be confused with a platen and is not configured to receive a
skin site. Accordingly, a finger may be placed within the target space
and imaged with one or more imagers. As discussed throughout this
disclosure in various embodiments, a contactless biometric system may use
various techniques to provide a user an indication of the location and/or
bounds of the target space. In other embodiments, the imagers singularly
or in combination may employ various techniques to image a finger and/or
hand depending on the relative location of the finger and/or hand to the
imagers.

[0092] FIGS. 7A, 7B, 7C and 7D illustrate various views of a contactless
biometric sensor apparatus according to one embodiment. In this
embodiment, the contactless biometric sensor includes four imagers 730,
optional optical elements 735, and four illumination sources 720. Any
number of imagers and/or illumination sources may be used. The simplest
contactless biometric sensor includes a single illumination source and a
single imager. The four imagers 730 may provide spatial modularity,
multispectral modularity, focal modularity or a combination of the above.
For example, each imager 730 may image a different area of the target
space. As another example, each imager may imager the finger under
distinct multispectral conditions.

[0093] FIGS. 8A, 8B, 8C and 8D illustrate various views of a
multispectrally modular, contactless biometric sensor apparatus with
multispectral imagers 830 that focus on different imaging planes
according to one embodiment. Various illumination elements 820 are shown.
As shown in the figure, the biometric sensor includes 16 imagers 830. In
this embodiment, four imagers 830A, 830P, 830E, 8300 are focused on first
imaging plane 880, another four imagers 830D, 830M, 830F, 830N are
focused on a second imaging plane 881, another four imagers 830H, 830C,
830G, 830I are focused on a third imaging plane 882, and yet another four
imagers 830B, 830L, 830K, 830J are focused on a fourth imaging plane 883.
For the sake of clarity, the focal plane for each imager is shown for
some, but not all imagers, in the figure. Each of the four imagers
focused at the same imaging plane are configured to provide an image
under a different multispectral condition. Thus, the imagers may be
configured to provide the same multispectral images of the finger at each
imaging plane. While 16 imagers are shown in the figure, any number of
imagers may be used with any combination focused at different imaging
planes and/or providing different multispectral images.

[0094] FIGS. 9A, 9B, 9C and 9D illustrate various views of a spatially
modular, contactless biometric sensor apparatus with imagers that focus
on different imaging planes according to one embodiment. Various
illumination elements 820 are shown. In this embodiment subsets of four
imagers are focused on different imaging planes as described above in
regard to FIGS. 8A, 8B, 8C and 8D. However, in this embodiment each of
the four imagers in each subset are focused on a different spatial
portions of the imaging plane, thus providing spatial modularity. As can
be seen in FIG. 9C, in this embodiment, imagers 830D and 830P are focused
on different portions of imaging plane 882, and imagers 830H and 830L are
focused on different portions of imaging plane 883. As can be seen in
FIG. 9D, in this embodiment, imager 830D is focused on imaging plane 882,
imager 830C is focused on imaging plane 881, and imagers 830A and 830B
are focused on different portions of imaging plane 881.

[0095] In any embodiment, each of the imagers may be a small wafer-level
camera. Moreover, the entire array of imagers may be provided on a single
wafer and/or circuit board. For example, such imagers may be OptiML®
wafer-level camera produced by Tessera® or the like. Various other
wafer-level cameras may also be used. In other embodiments CMOS sensors
and/or CCD sensors may be used as imagers.

[0096] Various other contactless systems may be used. For example, imagers
with auto focus may be used to focus light from a finger and/or hand at a
various distance from the imager. In another embodiment, an imager may be
used that provides a large depth of field. In another embodiment, an
imager may be used that has a large numerical aperture. In yet another
embodiment, wavefront coding transfer functions may be used.

[0097] Spatially Modular Hand Sensor

[0098] FIGS. 11A, 11B, 11C and 11D illustrate various views of a spatially
modular biometric hand sensor apparatus according to one embodiment. The
biometric hand sensor, according to this embodiment includes a large
platen 1110 with a target surface 1112 for receiving a hand 915. A
plurality of light sources 1120, optional optical elements 1135, and
imagers 1130 are also included. Each imager may be focused on a different
portion of the target surface 1112. In some embodiments, the portions of
the target surface imaged by the imagers 1130 overlap and/or cover the
entire target surface 1112 as shown in the figures. In other embodiments,
the portions of the target surface imaged by the imagers 1130 do not
overlap. In yet another embodiment, the portions of the target surface
1112 imaged by the imagers do not cover the entire target surface 1112,
instead they cover only specific portions of the target surface. Any
number of illumination sources may be used to illuminate a hand 1115 on
the target surface 1112. Depending on the design and/or needs, more or
less imagers 1120 may be used to image the target surface 1112. Due to
the modularity of the imagers, additional imagers may be added.

[0099] A spatially modular biometric sensor may provide images of portions
of hand 2005, 2010, 2015, 2020, 2025, 2030 according to one embodiment,
as shown in FIG. 21. Each image includes a similarly sized imager of a
portion of a hand. Some overlap between images may occur as shown in FIG.
20. In another embodiment, specific locations of a hand are imaged by a
different imager as shown in FIG. 18. Three images are produced for each
finger. For example, the pinky (the smallest, left-most finger) is imaged
in three areas 1825, 1826, 1827 corresponding to the portion of the
finger between the knuckles or joints. The other fingers have similar
coverage. The thumb is imaged in two areas 1825, 1836 between joints. The
body of the hand is imaged in three locations, the hypothenar 1830, palm
core 1831, and thenar 1832. Any other combination of images of the hand
may be devised.

[0100] As shown in FIG. 19, a multispectral hand sensor, whether
contactless or not, may provide a datacube 1900 that includes images that
correspond to each of the multispectral conditions used to image the hand
in the measurement process. In the figure, five separate images 1905,
1910, 1915, 1920, and 1925 are shown, corresponding to five multispectral
conditions. In an embodiment where visible light is used, the images
might correspond, for example, to images generated using light at 450 nm,
500 nm, 550 nm, 600 nm, and 650 nm. For example, each imager may include
a color filter. In other embodiments the images may represent
polarization conditions, imaging angle, and/or TIR conditions. In some
embodiments, each image may represent the optical effects of light of a
particular wavelength interacting with skin and. Due to the optical
properties of skin and skin components that vary by wavelength,
polarization, and/or angle of imaging, each of the multispectral images
1905, 1910, 1915, 1920, and 1925 will be, in general, different from the
others.

[0101]FIG. 12 shows a block diagram of a biometric hand sensor system
including a computational device 502, such as the one shown in FIG. 5,
according to one embodiment. In this embodiment, 16 imagers 510 and
processors 515 with memory 520 are coupled to the computational device
502. In another embodiment, imager memory 520 may be shared amongst
imagers 515 and/or with the computational device 502.

[0102] Contactless Hand Sensor

[0103] FIGS. 13A, 13B, 13C and 13D illustrate various views of a
multispectrally and/or spatially modular contactless biometric sensor
apparatus according to one embodiment. In this embodiment, the
contactless biometric hand sensor includes four imagers 1330 and four
illumination sources 1320. Any number of imagers and/or illumination
sources may be used. The simplest contactless biometric hand sensor
includes a single illumination source and a single imager. The four
imagers 1330 may provide spatial modularity, multispectral modularity,
focal plane modularity or a combination of the above. For example, each
imager 1330 may image a different area of the target space. As another
example, each imager 1330 may imager the hand under distinct
multispectral conditions. As another example, each imager 1330 may image
a different focal plane.

[0104] FIGS. 14A, 14B, 14C and 14D illustrate various views of a spatially
and multispectrally modular, contactless biometric sensor apparatus
according to one embodiment. Sixteen imagers 1420, and sixteen optional
optical elements 1435 are shown along with eight illumination sources
1420. Any number of illuminations sources 1420 of any type may be used.
Various optical elements 1435 may also be used.

[0105] FIGS. 15A, 15B, 15C and 15D illustrate various views of a spatially
and/or multispectrally modular, contactless biometric sensor apparatus
with imagers that focus on different imaging planes according to one
embodiment. For convenience in describing these embodiments, four imagers
1520 are shown in groups 1560 outlined by doted lines. For example, a
first group 1560A includes imagers 1520A1, 1520A2, 1520A3, and 1520A4.
Each of these imagers provides imaging coverage for a first zone in
target space corresponding to their placement in the imager array 1500,
yet each imager 1520 is also focused on different imaging plane. Thus,
the imagers 1520 within a group 1560, provide coverage for a specific
lateral zone, possibly with overlap, they also provide coverage for
vertical distance from the imagers by focusing at different focal planes.
While the figure shows four imagers 1520 placed in a group 1560, any
number of imagers may used. Moreover, any number of groups 1560 may be
used as well. Due to the modular nature of the system, imagers 1520 and
groups 1560 may be added as needed.

[0106] In another embodiment, each imager 1520 within a group 1560 may
image the hand under a different multispectral condition. For example,
imager 1520A1 may provide an image of red light from the area of the hand
corresponding to the group 1560A location in the imager array 1500.
Imager 1520A2 may provide an image using a polarizer of the area of the
hand corresponding to the group 1560A location in the imager array 1500.
Imager 1520A3 may provide an image with a resolution of 2,000 PPI or
higher, while other imagers provide imagers with a resolution less than
2,0000 PPI. Imager 1520A4 may provide an image of green light from the
area of the hand corresponding to the group 1560A location in the imager
array 1500. Various other multispectral conditions may be used as well.
Imagers within a group, according to another embodiment, are not
necessarily contiguous as shown. Moreover, in another embodiment, the
placement of the imagers 1520 within the imager array 1500 may be placed
at different locations or elsewhere than within a close planar imager
array 1500 as shown.

[0107] In another embodiment, the imager array 1500 may provide imagers
1520 that provide spatial, multispectral and focal plane modularity. For
example, the imagers may image spatial zones of a hand within the target
space. Subset of these imagers may be focused at various focal planes
with various multispectral conditions. That is, each imager may image a
spatial zone at a set focal plane using one multispectral condition.
Those skilled in the art will recognize the various combinations that can
be implemented.

[0108] Proximity Sensor User Interface

[0109] FIG. 16 shows a contactless biometric system user interface with a
holographic image of a hand 1615 according to one embodiment. As shown, a
number of illumination sources 1620, imagers 1630 and optical elements
1635 are shown. The imagers 1630 and illumination sources 1630 are
configured to illuminate and image a hand and/or finger placed within the
target space 1612. Holographic image generator (not shown) is included
that provides a holographic image of a hand 1615 within the target space
1612. Thus, a user may place their hand within the target space 1612 by
placing their hand on, near, or within the holographic hand image 1615.
The holographic image generator may also provide a volumetric display or
image. An optional structure 1640 is shown in the figure. Other
embodiments may use a holographic image of a finger rather than a hand.

[0110] FIG. 17 shows a contactless biometric system user interface with a
light array 1750 according to one embodiment. As shown, a number of
illumination sources 1720, imagers 1730 and optical elements 1735 are
shown. The imagers 1730 and illumination sources 1730 are configured to
illuminate and image a hand and/or finger placed within the target space.
Two light sources 1745, for example two lasers or laser diodes, each
provide a light beam 1750 that at least partially defines some boundaries
of the target space. Any number of light sources may be used in any
configuration. As a user moves their hand or finger into the target
space, the user can see the light beam on their hand or finger and know
that they are approaching a boundary of the target space. An optional
structure 1740 is shown in the figure.

[0111] Various other user interface elements may be implemented. For
example, in one embodiment a proximity sensor may be implemented in
conjunction with a speaker or other visual interface. The proximity
sensor, for example, may user stereoscopic imagers and/or stereoscopic
light sources. When the proximity sensor detects the presence of an
object within the target space, the illumination sources may illuminate
the object and the imagers may image the object within the target space.
An audible interface, for example, a speaker, may also be used to alert
the user that an image has been taken, that the user's hand and/or finger
is within the target space, and/or to ask the user to move their hand
and/or finger to align it within the user space.

[0112] Proximity Sensor

[0113] A proximity sensor and/or presence sensor may also be included in
various embodiments. In contactless biometric systems, it is important to
know whether a biometric feature of interest is within a target space. A
proximity sensor may make such a determination. For example, a proximity
sensor may incorporate stereoscopic imagers and/or stereoscopic
illumination sources. The system may then analyze when peak intensities
approach a calibrated area of an image associated with the target space.
A stereoscopic illumination proximity sensor may include at least two
illumination sources located a distance apart form each other and an
imager placed between the two illumination sources. As an object under
illumination by such stereoscopic illumination sources, approaches the
imager a graph of the peak intensities across the imager converge. The
system may then determine whether the object is within the target space
by making a comparison with calibrated data.

[0114] A stereoscopic proximity sensor may include at least two imagers
sources located a distance apart form each other and an illumination
source placed between the two imagers. As an object under illumination,
approaches the illumination source and/or imagers, a combined graph of
the peak intensities of the two imagers begin to converge. Moreover, a
single imager and two illumination sources may be used. Similarly, a
graph of the intensity versus lateral imager position will provide
converging peaks as an object approaches the imager and/or illumination
sources. The system may determine whether an object is within the target
space by making a comparison with calibrated data. Various other
proximity detection techniques are provided in previously incorporated
U.S. patent application Ser. No. 12/100,597.

[0115] In yet another embodiment, a light source may illuminate the target
space with a large angle of incidence, for example, greater than
60° from the normal of the target space. The light source, in
various embodiments, may be a monochromatic blue light source or, in
another embodiment, the light source may emit monochromatic light less
than about 600 nm. The light source or sources illuminate not only the
target space but also the area immediately above the target from beneath
the target space. A color filter array filters light from the target
space prior to the light being incident on an imager. The color filter
array may be any color filter array described in the various embodiments
described herein. The color filter array filters light according to
wavelength bands. Thus, the relative intensity of a wavelength band may
be compared with other wavelength bands. As a purported biometric feature
approaches the target, monochromatic light is reflected from the surface
of the biometric feature. Accordingly, the relative intensity of the
wavelength band containing the wavelength of the monochromatic light
increases relative to other frequency bands as the purported biometric
feature approaches the target. Accordingly, the intensity of blue light
is monitored relative to the intensity of red and/or green light. If the
intensity of blue light relative to the intensity of red and/or green
light increases, then a purported biometric feature is proximate to the
target space. If the blue light intensity does not increase enough, than
there is no purported biometric feature proximate to the target and the
system continues to monitor the intensity levels of various wavelength
bands.

[0116] FIG. 22 shows a flowchart of a biometric detection using various
embodiments. While a number of steps or processes are shown, embodiments
may include every step or process, additional steps or processes, or only
a one or more steps or processes. Moreover, each step or process may
include various sub-steps or sub-processes. At block 2205 the location of
the target space is indicated to a user. This indication may include, for
example, a holographic image, light beam array, audio indications, visual
indications, a platen, a prism, etc. The presence of an object within the
target space, such as a skin site, is sensed or detected at block 2208.
The presence of an object within the target space may be sensed using
stereoscopic imagers and/or stereoscopic illumination sources and/or
multispectral techniques. The skin site is illuminated at block 2210. The
illumination may occur prior to any other step described herein and/or
may occur only after the presence of a skin site is detected. Various
illumination sources may be used under any variety of multispectral
conditions, such as, wavelength, wavelengths, polarization, angle, etc.
During illumination the skin site is imaged using two imagers at block
2215A and 2215B. These imagers may image the skin site substantially
simultaneously. That is, these imagers may see the object in multiple
ways under a single illumination sequence. Any number of imagers may be
used. The imagers may image the skin site under any variety of
multispectral conditions, such as, wavelength, wavelengths, polarization,
resolution, spatial modularity, focal plane modularity, imaging angle,
etc. A multispectral image may be derived from the images produced from
the imagers at block 2220. A biometric function may then be performed at
block 2225. The biometric function may include identification of an
individual, associating an individual with an access code, associating an
individual with a group of individuals, determining whether access to a
facility, building, resort, activity, automobile, security area, and/or
device is permissible, performing a liveliness determination, performing
a spoof determination, biometric matching (identification or
verification), and/or estimation of demographic parameters including age,
gender and ethnicity, etc.

[0117] Exemplary Hardware

[0118] Various embodiments described herein use a light source to
illuminate a target area, target surface, platen, skin site, finger,
hand, etc. Such illumination sources may include a broad-band source such
as an incandescent bulb, a white-light LED, a glowbar, or others of the
sort. Alternatively, the illumination source may comprise one or more
narrow-band sources such as LEDs, lasers and laser diodes, quantum dots,
optically filtered sources and the like. In some cases, the illumination
system may incorporate optical polarizers in such a way that the light
from one or more sources is polarized before impinging on the hand. In
some cases the polarizer may be a linear polarizer or a circular
polarizer. In some embodiments, multiple light sources are illuminated
simultaneously during normal operation. In other cases, the multiple
light sources may be illuminated in some sequence, during which a
multiplicity of images are captured and recorded. In some embodiments
more than one illumination source is shown in a figure or described, in
such embodiments, a single light source may also be used.

[0119] Some embodiments described herein require one or more imagers.
These imagers may comprise, for example, a silicon CMOS imager or a
silicon CCD imager. Alternatively, the imager may comprise a photodiode
array made of materials such as MCT, lead-salt, InSb, InGaAs, or a
bolometer array, or other devices and materials that enable the capture
of images corresponding to the desired illumination wavelengths. In
another embodiment a wafer-level imager or an array of wafer level
imagers may be used. In addition to the imaging array, there may be one
or more polarizers present in the imaging system and located such that
the imager "views" the hand or a portion thereof through the polarizer.
Such polarizers may be linear or circular polarizers. In some cases, the
polarizer in the imaging system may be arranged such that it is
substantially orthogonal or crossed relative to one or more polarizers
present in the illumination system. In some cases, the imager polarizer
may be arranged to be substantially parallel or the same orientation as
the illumination polarizer.

[0120] In cases where the imager views the hand through a polarizer that
is substantially crossed relative to the illumination polarizer, the
resulting image tends to emphasize image features that lie below the
surface of the skin. In cases where the imager views the hand through a
polarizer that is substantially parallel to the illumination polarizer,
the resulting image tends to emphasize image features that lie at or near
the surface of the skin. In cases where either the illumination polarizer
or image polarizer or both are omitted, the resulting image tends to
contain effects from both surface and subsurface features. In some cases,
it may be advantageous to collect and analyze images collected under
different polarization conditions in addition to or instead of images
taken with different illumination wavelengths.

[0121] In some cases, an imager may be a color imager capable of
separating multiple wavelength bands. The use of such a color imager may
be used in cases that a broad-band illumination source is used or
multiple, different narrow-band illumination sources are turned on
simultaneously. In such cases, information from multiple illumination
conditions may be collected simultaneously, reducing the time and/or data
volume requirements of an equivalent sequential series of monochromatic
images. In some cases the color imager may be obtained by combining a
digital imager with broad wavelength response with a color filter array
that provides a narrower wavelength response to each imager pixel. In
some cases the color filter array may contain three different
color-selective filters (red, green and blue) in a Bayer pattern as known
to one familiar in the art. Other variations of a color filter array as
well as other means of color separation may also be advantageously
employed.

[0122] Both the illumination and imaging systems may include other optical
components such as lens, mirrors, phase plates, shutters, diffusers,
band-pass optical filters, short-pass optical filters, long-pass optical
filters, and the like in order to direct, control and focus light in a
manner known to one familiar in the art.

[0123] In addition to the illumination and imaging subsystems, there may
be a platen on which the hand is placed for imaging. Alternatively, the
platen may be omitted and the hand imaged in free space.

[0124] In various embodiments, the light sources and/or illumination
sources are white-light LEDs. There may be two banks of LEDs: one with a
linear polarizer present and one without a polarizer. Both banks of LEDs
illuminate a platen through diffusers, lenses and/or mirrors to achieve
moderately consistent illumination over the platen area. The platen may
be a plane glass plate. The imagers described throughout this disclosure
may be color silicon CMOS or CCD imagers, monochromatic imagers,
wafer-level cameras, etc. Lenses and/or mirrors are used to image the top
surface of the platen onto the imager may also be used in embodiments
described herein. A short-pass filter is placed in the imaging system to
significantly reduce the sensitivity of the imager to infrared light may
be used. A linear polarizer may be placed in the imaging system such that
it is substantially orthogonal to the polarizer present in one of the
illumination banks. In other embodiments, the imaging system and number
of pixels may be designed to image at a resolution of between 100 and
2,000 pixels per inch (PPI). In other embodiments, the imaging system may
be designed to image the hand with a resolution of approximately 500 PPI.
A series of two images may be collected: one with the non-polarized white
light illuminating the hand and one with the cross-polarized light
illuminating the hand. Optionally, a third image may be collected with
all illumination LED's turned off, resulting in an image that represents
the effect of ambient light. In some cases, the ambient-light image (or
some grey-level scaled version of it) may be subtracted from one or both
of the illuminated images to produce an estimate of corresponding images
in which no ambient light is present.

[0125] Moreover, one or more imagers in any of the various embodiments may
include a high resolution imager. As noted above, a multispectral image
can be derived from images with different resolutions. That is, imagers
with various resolutions may be used to derive a multispectral image.
Such imagers may be used, for example, to image the hand(s) and/or foot
(feet) of infants, including neonatal and/or premature infants. In one
embodiment, a high resolution imager may be capable of imaging at least
1,000 pixels per inch (PPI). Such images may be capable of showing pores
and/or the shape of ridges in a finger and/or hand or foot. In another
embodiment, a high resolution imager may be capable of imaging at least
2,000 PPI, which may show pores and/or the shape of ridges in the finger
and/or hand or foot of a neonatal or premature infant. In another
embodiment, a high resolution imager may be capable of imaging at least
3,000 PPI. In another embodiment, a high resolution imager may be capable
of imaging at least 4,000 PPI.

[0126] Various embodiments may be provide identification of an individual
by analyzing an image of the individual's fingerprint, handprint and/or
palm print. Such embodiments may compare minutiae points, fingerprint,
palm print and/or handprint patterns, multispectral characteristics of an
finger, hand and/or palm, etc. Other identifying features may also be
used as skin discolorization, deformation, scars, marks, tattoos, moles,
warts, freckles, etc. Anything within an image that may aid in the
biometric determination may be considered.

[0127] FIG. 23 shows an image of a finger 2300 with a tattoo-like feature
2310 according to one embodiment. A tattoo-like feature, a tattoo, or
other markings may aid in a biometric determination. FIG. 24 shows an
image of a hand 2400 with a number of moles 2405 and a scar 2410
according to another embodiment. Moles 2405, scars 2410, markings, and/or
other discolorizations may also be used to aid in a biometric
determination. Features such as tattoos, scars, and/or marks can be used
as a highly reliable differentiator between individuals.

[0128] Certain existing sensor products that use multispectral imaging use
contact as a mechanism of position registration to simplify several
aspects of the system design. Multispectral imaging fingerprint
technology also offers the industry's best protection against spoof
attempts due to the extensive information that is captured with
multispectral imaging. Such imaging yields extensive data from the
surface and the subsurface optical characteristics of the finger or spoof
material from which the fingerprint is acquired that makes
differentiating genuine from fake readily done.

[0129] The sensor described herein provides a true contactless fingerprint
sensor that is fast, intuitive, and easy to use, while capturing
fingerprints that are fully compatible with historical Automated
Fingerprint Identification System ("AFIS") systems. The sensor eliminates
artifacts due to finger movement and facilitates easy and reliable user
interaction. this rapid acquisition capability is obtained in one
embodiment through the use of multiple imagers that are synchronized to
simultaneously capture all required images.

[0130] For example, a plurality of the imagers may be used to monitor the
space over the sensor, which may be further actively illuminated at some
wavelength or illuminated by ambient light. The plurality of imagers may
be used to detect motion in the space above the sensor and initiate a
sensor arming sequence when such motion is detected. The plurality of
imagers may further be used to determine the approximate location of the
object in the space above the sensor based upon the differing (parallax)
views of the imagers. The images from the plurality of sensors may be
analyzed to determine when an object above the sensor is in the preferred
space to trigger the sensor acquisition. In some embodiments, the images
from the plurality of imagers will also be analyzed to determine if the
object in the space above the sensor has the optical characteristics of
the finger and will only trigger an acquisition when the object is
consistent with a finger and in the proper location.

[0131] In one embodiment, the illumination subsystem comprises one or more
light-emitting diodes that illuminate the region of interest above the
sensor with light of the required characteristics. The light-emitting
diodes may sometimes comprise white-light emitting diodes. Alternatively
or additively, one or more of the light-emitting diodes may be a
narrow-band or monochromatic light source. In cases where a plurality of
such light sources are used, the light sources may be substantially the
same or they may have substantially different wavelength characteristics.
In some cases, such light-emitting diodes may comprise sources that emit
in red, green, and blue wavelengths. In some cases, one or more
light-emitting diodes may emit at wavelengths other than visible
wavelengths such as in the near ultraviolet or the near infrared. In any
of these illumination configurations, one or more illumination source may
be linearly polarized using a sheet polarizer (not shown).

[0132] In one embodiment, the imaging system may comprise a plurality of
imagers. The imagers may be silicon arrays and may be fabricated as
digital CMOS devices or CCD devices. One or more of the imagers may be
panchromatic ("black and white") imagers. Some of the panchromatic
imagers may incorporate a wavelength filter to limit the wavelengths that
are substantially seen by the imager. The non-limited wavelengths may be
a portion of the visible wavelength region. Alternatively, the
non-limited wavelengths may comprise wavelengths in the near ultraviolet
or near infrared wavelength regions. One or more of the imagers may be
color imagers. The color imager may comprise a color filter array
consisting of red, green and blue pixels arranged in some pattern such as
a Bayer pattern. Alternatively, the color imager may be comprised of an
arrangement of chromatic beam splitters and multiple panchromatic
imagers, as known to one familiar in the art. While the discussion below
sometimes makes specific reference to "color imagers" in providing
examples of specific embodiments, it should be understood that these
embodiments are merely exemplary and that other embodiments may
incorporate some or all of the imager variations described herewith or
others that will be obvious to one familiar in the art.

[0133] In a particular embodiment, the imaging subsystem comprises some
number of color imagers that are oriented and focused on the trigger
point of the three-dimensional sensing subsystem. When the position
sensor is triggered, all imagers will substantially simultaneously
capture an image of the finger that triggered the sensor. This rapid and
substantially simultaneous collection of multiple images will mitigate
motion artifacts and increase the overall robustness and
user-friendliness of the sensing system. Some portion of the color images
may sometimes have optical polarizer attached to them (not shown) in
order to provide the ability to capture images in a crossed-polarized
modality.

[0134] In some embodiments, the plurality of imagers may be oriented such
that they all substantially image a similar region above the sensor. In
other embodiments, some or all of the imagers may image different regions
of space. In some embodiments the imaged regions may substantially
overlap. In some embodiments the imagers may image different regions of
space that are all substantially at the same focal distance or "height"
above the sensor. In so doing, the sensor system may be able to capture a
bigger object field than would be possible if the same imagers were
focused on the same region of space. In some embodiments the imagers may
image regions of space at different distances (heights) from the sensor,
which enables the sensor to acquire data over a larger range of focal
distances than provided for if all imagers were focused at the same focal
distance.

[0135] Methods for obtaining a reliable and intuitive user interface are
believed to include providing the user with a guide to proper orientation
and placement of a finger through the use of a hologram that shows a hand
and finger in the proper place above the sensor. This would permit the
user simply to place his finger in a similar position, which will then
trigger the measurement sequence.

[0136] Thus, having described several embodiments, it will be recognized
by those of skill in the art that various modifications, alternative
constructions, and equivalents may be used without departing from the
spirit. For example, the principles described herein could be applied to
four-finger acquisition, to whole-hand imaging, or to imaging of the skin
on other body parts. Accordingly, the above description should not be
taken as limiting the scope, which is defined in the following claims.